steels wheels are they all painted body color?

I own a 1968 280SL. In all the early photographs of these cars on the assembly line it looks like the steel wheels are painted body color.
My wheels are black unpainted. Is this correct for 1968 or should they be sprayed body color and does the hole wheel have to be painted or just the outside where the hub caps fit over the wheel, my wheel cover are full trim covers.